/usr/include/boost/atomic/detail/gcc-cas.hpp is in libboost1.54-dev 1.54.0-4ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 | // Copyright (c) 2011 Helge Bahmann
// Copyright (c) 2013 Tim Blechmann
//
// Distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
// Use the gnu builtin __sync_val_compare_and_swap to build
// atomic operations for 32 bit and smaller.
#ifndef BOOST_ATOMIC_DETAIL_GENERIC_CAS_HPP
#define BOOST_ATOMIC_DETAIL_GENERIC_CAS_HPP
#include <cstddef>
#include <boost/cstdint.hpp>
#include <boost/atomic/detail/config.hpp>
#ifdef BOOST_ATOMIC_HAS_PRAGMA_ONCE
#pragma once
#endif
namespace boost {
#define BOOST_ATOMIC_THREAD_FENCE 2
inline void
atomic_thread_fence(memory_order order)
{
switch(order) {
case memory_order_relaxed:
break;
case memory_order_release:
case memory_order_consume:
case memory_order_acquire:
case memory_order_acq_rel:
case memory_order_seq_cst:
__sync_synchronize();
break;
}
}
namespace atomics {
namespace detail {
inline void
platform_fence_before(memory_order)
{
/* empty, as compare_and_swap is synchronizing already */
}
inline void
platform_fence_after(memory_order)
{
/* empty, as compare_and_swap is synchronizing already */
}
inline void
platform_fence_before_store(memory_order order)
{
switch(order) {
case memory_order_relaxed:
case memory_order_acquire:
case memory_order_consume:
break;
case memory_order_release:
case memory_order_acq_rel:
case memory_order_seq_cst:
__sync_synchronize();
break;
}
}
inline void
platform_fence_after_store(memory_order order)
{
if (order == memory_order_seq_cst)
__sync_synchronize();
}
inline void
platform_fence_after_load(memory_order order)
{
switch(order) {
case memory_order_relaxed:
case memory_order_release:
break;
case memory_order_consume:
case memory_order_acquire:
case memory_order_acq_rel:
case memory_order_seq_cst:
__sync_synchronize();
break;
}
}
template<typename T>
inline bool
platform_cmpxchg32_strong(T & expected, T desired, volatile T * ptr)
{
T found = __sync_val_compare_and_swap(ptr, expected, desired);
bool success = (found == expected);
expected = found;
return success;
}
class atomic_flag
{
private:
atomic_flag(const atomic_flag &) /* = delete */ ;
atomic_flag & operator=(const atomic_flag &) /* = delete */ ;
uint32_t v_;
public:
BOOST_CONSTEXPR atomic_flag(void) BOOST_NOEXCEPT : v_(0) {}
void
clear(memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
{
atomics::detail::platform_fence_before_store(order);
const_cast<volatile uint32_t &>(v_) = 0;
atomics::detail::platform_fence_after_store(order);
}
bool
test_and_set(memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
{
atomics::detail::platform_fence_before(order);
uint32_t expected = v_;
do {
if (expected == 1)
break;
} while (!atomics::detail::platform_cmpxchg32(expected, (uint32_t)1, &v_));
atomics::detail::platform_fence_after(order);
return expected;
}
};
#define BOOST_ATOMIC_FLAG_LOCK_FREE 2
}
}
}
#include <boost/atomic/detail/base.hpp>
#if !defined(BOOST_ATOMIC_FORCE_FALLBACK)
#define BOOST_ATOMIC_CHAR_LOCK_FREE 2
#define BOOST_ATOMIC_SHORT_LOCK_FREE 2
#define BOOST_ATOMIC_INT_LOCK_FREE 2
#define BOOST_ATOMIC_LONG_LOCK_FREE (sizeof(long) <= 4 ? 2 : 0)
#define BOOST_ATOMIC_LLONG_LOCK_FREE (sizeof(long long) <= 4 ? 2 : 0)
#define BOOST_ATOMIC_POINTER_LOCK_FREE (sizeof(void *) <= 4 ? 2 : 0)
#define BOOST_ATOMIC_BOOL_LOCK_FREE 2
#include <boost/atomic/detail/cas32strong.hpp>
#endif /* !defined(BOOST_ATOMIC_FORCE_FALLBACK) */
#endif
|